The present invention relates to an automatic sheet feed mechanism and more particularly to an automatic sheet feed mechanism using a pick roller apparatus for both advancing sheets and for sensing the height of a stack of sheets in its hopper.
Photocopiers and other devices such as automatic test scoring machines utilize automatic sheet feed mechanisms to provide a single sheet at the appropriate rate for operation on by the machine. Sheet feed mechanisms utilize a feeding mechanism for advancing the uppermost sheet of a stack of sheets to be operated on and a hopper table lift mechanism for raising the hopper table such that the stack of sheets are maintained at the proper height for operation on by the sheet feed mechanism. Typically, the sheet feed mechanism will include a pick roller for engaging the uppermost sheet and separator rollers for separating the uppermost sheet from any other sheet that might be inadvertently adhering thereto.
Automatic sheet feed mechanisms have long been used. However, many of these devices are rather intricate having many interacting parts. These devices are subject to frequent breakdown. Accordingly, the maintenance costs are quite high as well as their initial purchase cost. One factor which has contributed to this complexity is the use of a separate pick roller for advancing sheets and a sensor roller for sensing the top surface of the stack of sheets in the hopper. Furthermore, these devices frequently utilize a separate drive mechanism for feeding of the sheets and adjustment of the hopper table height which results in increased parts. Additionally, should some part become stuck or accidentally locked for whatever reason, the sheet feed mechanism is subject to substantial damage.
In addition, currently available automatic sheet feed mechanisms often have space requirements which are cumbersome and prohibitive to their use in certain applications.
These and many other problems are solved by the present invention.